As an experiment:

Use a pose file that does work and text edit it to inject your new PMD and to set the morphs.

If that does work, then you know that it is the PMDedit script

(which I am guessing is not the problem)

If it does not, then it is likely that the pmd are not backwards compatible.

It would probably be better to stop trying to carry a long baggage train and cut off at P9/PP2012 anyway.